Confused by 3 micron diamond stones

[blacksheep25]

This looks pretty weird to me. I’ve never seen that on a diamond stone. Can you see what is scratched? Is it something with the diamonds or is it the backing material?

I looked at the scratches under a 10x loupe, and it must be the base material. I have not noticed that on any of the other DMT products I have. The knife in the pic is a VG-10 spyerco delica, and I was going pretty light since the initial few sharpens on new diamond stones are when you can knock off the diamonds since they’re still “high” and haven’t been worn down yet. Actually, even on my broken-in stones, I still don’t go hard at all (“let the diamond/cutter do the work”).

Good point Blacksheep. I wonder where these fit into the progression? Maybe they do need to come before ceramics?

How do they compare to the 1000 grit diamond stones? Do they seem finer?

I compared the 800, 1000 and 3u, and when you run your fingers over the stones, the 3u does seems smoother than the 1000. I’d probably use the natural progression of (note: “-d” for diamond and “-c” for ceramic):

800-d > 1000-d > 3u-d > 1600-c > 1200-c > 1.4u-c > 0.6u-c > strop

Completely agree with the observations that you cannot compare cutting material size since it’s not apples-to-apples, and diamond will behave different from ceramic. When I have some time, I’m going to take beater knife and sharpen it in progression, then when I move to the next finer grit, I will leave behind a part of the blade at the coarser, in the end, you should see the progression back to back. Maybe someone with a USB microscope could do this as well, but I’m thinking you can still see it with a standard camera.

[wickededge]

This is all great stuff. There are several reasons why diamond plates work differently vs. ceramics vs. strops vs. films etc…:

Hardness/friability – Diamonds are much harder and don’t break down into smaller pieces (very easily anyway) compared with ceramics

Substrate/matrix – Ceramic abrasives are part of a matrix so the whole particle isn’t sitting above the plane of the substrate. The diamonds on steel plates have their entire thickness above the base level of the substrate and they are also harder so the depth (and therefore width) of the scratch will be bigger from a diamond plate vs. the softer, partially embedded, and therefore not full thickness, aluminum oxide particle of the same size in a ceramic stone. The diamonds on a film will compress into the film so the entire diamond isn’t exposed and isn’t pushed into the metal with as much force. The same is even more true with strops.

So when you have a bunch of 3um aluminum oxide particles fused or bound into a matrix, the size and hardness of the particles contacting the blade will be very different from the size and hardness of a 3um diamonds bound to the surface of a steel plate. The diamonds will stick up more, cut more deeply and give a wider scratch.

Another thing about ceramics is that the particles can be dramatically altered during sintering. They often fuse together creating larger particles or strange shapes that, when exposed in the matrix, can manifest as smaller particles.

Attachments:

• Ceramic-vs-Diamond.png

-Clay

[Joel Casto]

Thank you. It’s important to know, but better to know why!

[Geocyclist]

Looks like I need to get some. A good step after 1000 diamonds before going to ceramics. Or for when I stop at 1000 diamonds, I might add these, then stop. Also interested if anyone uses them for touch ups as a starting point. I have touched up a few blades with ceramics, but usually damage the edge enough I have to go back to 400/600 diamonds or so.

[Andy Steffen]

I’ve been absent from the hobby for about a year so hopefully I didn’t just miss the answer I’m looking for, but what are you guys using on the glass side of these stones? Everything I’ve read makes sense here as far as using the 3 micron stones between the 1000 grit diamonds and the ceramics – I have the 1200/1600 ceramics – but I’ve never used a lapping film before so I can only guess at how it compares or fits into the mix.

Given what I’ve read on it, it seems like maybe a good progression would be:

1000 D -> 3 micron D -> 1200/1600 C -> 3 micron lapping film? -> 5 micron leather strops

Or maybe I should go ahead and add the microfine ceramics into the mix and go with a lower grit stropping film:

1000 D -> 3 micron D -> 1.4 micron C[/i ]-> 1200/1600 C -> .6 micron C -> 1 or .5 micron lapping film? -> 5 micron leather strops

[Fred Hermann]

I’ve been infrequent on the forums of late, and this is great data.
Tagged for later reference…
🙂

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